Roof heating tapes are used widely by being installed on the overhanging eave of a sloped roof for melting accumulations of ice and snow which form there at ambient temperature conditions which are conducive to melting ice and snow on the portion of the roof over heated premises, where warming is provided by heat loss through the roof, but which do not prevent freezing of run-off water at the unheated eave and in the rain gutter and downspout. An ice dam will form backing further run-off water up the slope of the roof and under the roof covering causing leakage. Heating tapes are commonly provided with manually controlled switches with little attention being paid to energy efficient control and use.